1. Field
The invention is in the field of light collecting reflectors for use with sources of light, the reflectors being adapted to direct light from a light source as a directional light beam.
2. State of the Art
Numerous reflectors have been devised for directing light from a light source as a directional beam of light. The most common reflectors in use today, particularly in the stage lighting and projection fields, utilize a reflecting surface which is a portion of an ellipse. The light source is located at the focus of the ellipse. The so-called ellipsoidal reflector has two major disadvantages. The first is that the majority of the light energy in a projected beam from such a reflector is concentrated in the center portion of the beam. This means that the center of the beam is brighter than the outer portion, resulting in uneven illumination. This concentration of energy in the center of the beam causes the center to contain more heat than the rest of the beam. The concentration of heat in the center can easily damage color media used with the light.
The second disadvantage of the ellipsoidal reflector is that its collection efficiency is only somewhere between 25 and 35 percent. This means that only 25 to 35 percent of the light given off by the light source ends up in the projected beam of light.
Reflecting surfaces utilizing other geometric shapes, such as portions of parabolas or spheres, have been used as well as have been various combinations of various geometric shapes. However, the shapes and combinations of shapes that have been used all leave room for improvement in both the light collection efficiency of the reflectors and in the uniform distribution of light intensity over the cross-section of a light beam projected by such reflectors. None of these reflectors have so far replaced the ellipsoidal reflector for general use in light projection equipment such as stage-lighting spotlights.
3. Objective
It was a principal objective of the invention to provide a light collecting reflector which produces an improved, substantially uniform, light distribution over the cross-section of a projected light beam, to provide a light collecting reflector with improved light collection efficiency, and to achieve these objectives with a reflector economical enough to replace the standard ellipsoidal reflector in a majority of applications.